Predictors of urinary heavy metal concentrations among pregnant women in Jinan, China.

BACKGROUND: Toxic heavy metal exposure and insufficiency or excess of essential heavy metals may have negative effects on pregnant women's health and fetal growth. To date, the predictors of pregnant women's heavy metal exposure levels remain unclear and vary with different regions. The study intended to explore potential predictors of exposure to heavy metals individually and high co-exposure to heavy metal mixtures. METHODS: We recruited 298 pregnant women in first trimester from prenatal clinics in Jinan, Shandong Province, China, and collected spot urine samples and questionnaire data on their demographic characteristics, lifestyle habits, consumption of food and dietary supplement, and residential environment. All urine samples were analyzed for seven heavy metals: cobalt (Co), molybdenum (Mo), strontium (Sr), arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg). RESULTS: Factors associated with single heavy metal concentration were as follows: a) urinary As, Sr and Cd increased with women's age respectively; b) pregnant women with higher monthly household income per capita had lower Sr and Mo levels; c) pregnant women with intermittent folic acid supplementation and those not taking tap water as domestic drinking water had lower Sr concentrations; d) Cd was positively linked with consumption frequency of rice; e) Hg was adversely related to consumption frequency of egg and the women who took purified water as domestic drinking water had lower Hg exposure. In addition, pregnant women's age was positively associated with odds of high co-exposure to Co, As, Sr, Mo, Cd and Pb; while those with an educational level of college had lower odds of high exposure to such a metal mixture compared with those whose educational levels were lower than high school. CONCLUSION: Predictors of single urinary heavy metal concentration included pregnant women's age (As, Sr and Cd), monthly household income per capita (Sr and Mo), folic acid supplementation (Sr), rice consumption frequency (Cd), egg consumption frequency (Hg) and the type of domestic drinking water (Sr and Hg). Pregnant women with older age, lower educational level tended to have high co-exposure to Co, As, Sr, Mo, Cd and Pb.

Equipment-free photothermal effect promoted self-healing and self-recovery of hydrogels.

The self-healing and self-recovery of the hydrogel materials can be promoted under sunlight without the assistance of electrical equipment by adding a light-to-heat conversion substance during the synthetic process, which will greatly extend the service life of the hydrogels even for the elastomer materials in the off-grid areas.

Engineering Lateral Heterojunction of Selenium-Coated Tellurium Nanomaterials toward Highly Efficient Solar Desalination.

Herein, a core-shell tellurium-selenium (Te-Se) nanomaterial with polymer-tailed and lateral heterojunction structures is developed as a photothermal absorber in a bionic solar-evaporation system. It is further revealed that the amorphous Se shell surrounds the crystalline Te core, which not only protects the Te phase from oxidation but also serves as a natural barrier to life entities. The core (Te)-shell (Se) configuration thus exhibits robust stability enhanced by 0.05 eV per Se atom and excellent biocompatibility. Furthermore, high energy efficiencies of 90.71 ± 0.37% and 86.14 ± 1.02% and evaporation rates of 12.88 ± 0.052 and 1.323 ± 0.015 kg m-2 h-1 are obtained under 10 and 1 sun for simulated seawater, respectively. Importantly, no salting out is observed in salt solutions, and the collected water under natural light irradiation possesses extremely low ion concentrations of Na+, K+, Ca2+, and Mg2+ relative to real seawater. Considering the tunable electronic structures, biocompatibilities, and modifiable broadband absorption of the solar spectrum of lateral heterojunction nanomaterials of Te-Se, the way is paved to engineering 2D semiconductor materials with supporting 3D porous hydrophilic materials for application in solar desalination, wastewater treatment, and biomedical ventures.

Addressable activated cascade DNA sequential logic circuit model for processing identical input molecules.

Herein, we propose the state and activation mechanisms able to realize the unification of an input signal and addressable sequential execution. Furthermore, a DNA sequential logic circuit (SLC) model was designed and applied in constructing a DNA register that for the first time realizes the generalized storage of identical input molecules.

A DNA arithmetic logic unit for implementing data backtracking operations.

We present the application of redundant modules in the molecular cascade circuit, which can help trace the results of each logic gate. This provides a basis for finding the error position and judging the final circuit result to improve the circuit and the reliability of the system.

A DNA kinetics competition strategy of hybridization chain reaction for molecular information processing circuit construction.

Herein we propose a hybridization chain reaction based kinetics competition strategy able to recognize the combination/sequence of input signals. Further, a DNA priority encoder and a keypad lock were constructed. This strategy allowed us to develop a one-pot assay that can automatically and smartly respond to multiple inputs.

Crystal structure analysis of a recombinant predicted acetamidase/formamidase from the thermophile Thermoanaerobacter tengcongensis.

The structure of acetamidase/formamidase (Amds/Fmds) from the archaeon Thermoanaerobacter tengcongensis has been determined by X-ray diffraction analysis using MAD data in a crystal of space group P21, with unit-cell parameters a = 41.23 (3), b = 152.88 (6), c = 100.26 (7) Å, ß = 99.49 (3) ° and been refined to a crystallographic R-factor of 17.4% and R-free of 23.7%. It contains two dimers in one asymmetric unit, in which native Amds/Fmds (TE19) contains of the 32 kDa native protein. The final model consists of 4 monomer (299 amino acids residues with additional 2 expression tag amino acids residues), 5 Ca²âº, 4 Zn²âº and 853 water molecules. The monomer is composed by the following: an N-domain which is featuring by three-layers ß/ß/ß; a prominent excursion between N-terminal end of strand ß7 and ß11, which contains four-stranded antiparallel ß sheet; an C-domain which is formed by the last 82 amino acid residues with the feature of mixed α/ß structure. The protein contains ion-pair Ca²âº-Zn²âº. The portion of three-layer ß/ß/ß along with the loops provides four protein ligands to the tightly bound Ca²âº, three water molecules complete the coordination; and provides five protein ligands to the tightly bound Zn²âº, one water molecule complete the coordination.

Structural insights into mechanisms of the small RNA methyltransferase HEN1.

RNA silencing is a conserved regulatory mechanism in fungi, plants and animals that regulates gene expression and defence against viruses and transgenes. Small silencing RNAs of approximately 20-30 nucleotides and their associated effector proteins, the Argonaute family proteins, are the central components in RNA silencing. A subset of small RNAs, such as microRNAs and small interfering RNAs (siRNAs) in plants, Piwi-interacting RNAs in animals and siRNAs in Drosophila, requires an additional crucial step for their maturation; that is, 2'-O-methylation on the 3' terminal nucleotide. A conserved S-adenosyl-l-methionine-dependent RNA methyltransferase, HUA ENHANCER 1 (HEN1), and its homologues are responsible for this specific modification. Here we report the 3.1 A crystal structure of full-length HEN1 from Arabidopsis in complex with a 22-nucleotide small RNA duplex and cofactor product S-adenosyl-l-homocysteine. Highly cooperative recognition of the small RNA substrate by multiple RNA binding domains and the methyltransferase domain in HEN1 measures the length of the RNA duplex and determines the substrate specificity. Metal ion coordination by both 2' and 3' hydroxyls on the 3'-terminal nucleotide and four invariant residues in the active site of the methyltransferase domain suggests a novel Mg(2+)-dependent 2'-O-methylation mechanism.

Expression, purification, crystallization and preliminary crystallographic study of a potential metal-dependent hydrolase with cyclase activity from Thermoanaerobacter tengcongensis.

The putative metal-dependent hydrolase gene TTE1006 from Thermoanaerobacter tengcongensis strain MB4T (T = type strain; Genbank accession No. AE008691) was heterologously expressed in Escherichia coli. The 205-amino-acid gene product was purified and crystallized. The crystal used for data collection belongs to space group P2(1), with unit-cell parameters a = 85.2, b = 62.1, c = 172.4 A, beta = 104.2 degrees. Using a synchrotron-radiation source, the resolution limit of the data reached 1.87 A. Eight molecules were estimated to be present in the asymmetric unit, with a solvent content of 48%. Structure determination is ongoing using the multiple-wavelength anomalous diffraction (MAD) method and also the molecular-replacement (MR) method.

Crystallization and preliminary crystallographic study of a recombinant predicted acetamidase/formamidase from the thermophile Thermoanaerobacter tengcongensis.

No crystal structures are yet available for homologues of a predicted acetamidase/formamidase (Amds/Fmds) from the archaeon Thermoanaerobacter tengcongensis. The Amds/Fmds gene was cloned and expressed as a soluble protein in Escherichia coli. Native Amds/Fmds and its SeMet-substituted form were purified and crystallized by vapour diffusion in hanging drops at 296 K. The native crystals, which were grown in PEG 8000, belong to the monoclinic space group P2(1), with unit-cell parameters a = 41.23 (3), b = 152.88 (6), c = 100.26 (7) A, beta = 99.49 (3) degrees. The diffraction data were collected to 2.00 A resolution using synchrotron radiation. Based on a predicted solvent content of 50%, a Matthews coefficient of 2.44 A3 Da(-1) and two main peaks in the self-rotation function, the asymmetric unit is predicted to contain two dimers of the 32 kDa native protein. MAD data were collected for the SeMet protein, but the corresponding crystals display different unit-cell parameters and appear to contain four dimers in the asymmetric unit.

Crystallization and preliminary crystallographic study of rBmKalphaIT1, a recombinant alpha-insect toxin from the scorpion Buthus martensii Karsch.

Alpha-insect scorpion toxins are a distinct group of scorpion neurotoxins for which no crystal structures are yet available. A novel alpha-insect toxin named BmKalphaIT1 from the scorpion Buthus martensii Karsch (BmK) has been expressed as an inclusion body in Escherichia coli and purified by chromatography after renaturation. Recombinant BmKalphaIT1 (rBmKaIT1) was crystallized using the vapour-diffusion technique in hanging drops at 296 K. The crystals, which were grown in sodium phosphate, belonged to the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 30.24 (1), b = 36.51 (3), c = 57.08 (2) A. Diffraction data were collected to 2.1 A resolution using synchrotron radiation. There appears to be one rBmKalphaIT1 molecule in the asymmetric unit.